1. Field of the Invention
The invention relates to an internal-combustion-engine misfire determination device and method, and to a vehicle including the device, and more specifically, to an internal-combustion-engine misfire determination device and method that determine the occurrence of a misfire in a multi-cylinder internal combustion engine, of which an output shaft is connected, through a torsion element, to a downstream shaft downstream of the torsion element, and to a vehicle including such a misfire determination device.
2. Description of the Related Art
As this kind of misfire determination device, a device has been proposed that, in a vehicle in which vibration control is performed using an electric motor so as to cancel variation in torque of a crankshaft of an engine, calculates the amount of correction of torque by which the torque output from the electric motor for vibration control using the electric motor is corrected, and detects misfires in the engine based on the amount of correction of torque output from the electric motor (see Japanese Patent Application Publication No. 2001-65402 (JP-A-2001-65402), for example).
In a system installed in a vehicle in which the crankshaft of the engine is connected to the downstream side through a torsion element, such as a damper, variation in torque of the crankshaft due to explosive combustion in the engine induces resonance of the torsion element and the downstream components including the torsion element, and the resonance causes variation in rotation of the crankshaft. As a result, even when it is tried to detect the occurrence of a misfire in one of the cylinders of the engine based on the variation in rotation of the crankshaft, the occurrence of a misfire cannot be accurately detected. When vibration control against variation in torque of the crankshaft of the engine is performed using an electric motor, resonance of the torsion element and the downstream components including the torsion element may be induced, and in this case, the accuracy in detecting the occurrence of a misfire in one of the cylinders of the engine is further reduced.